Efficient removal of cobalt from aqueous solution using β-cyclodextrin modified graphene oxide

Abstract

β-Cyclodextrin modified graphene oxide (denoted as β-CD–GO) was synthesized and applied as a sorbent to remove Co(II) from aqueous solution. The synthesized β-CD–GO was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDX), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) in detail, and the results of the characterization indicated that β-CD was successfully grafted onto the surface of GO. The effects of pH, ionic strength, competing ions and solid content on the sorption of Co(II) onto the β-CD–GO nanocomposites were investigated. The results indicated that Co(II) sorption on β-CD–GO was strongly dependent on pH and independent of ionic strength under the experimental uncertainties. The sorption isotherms of Co(II) on β-CD–GO could be described well by the Langmuir model. The thermodynamic data (ΔH⁰, ΔS⁰ and ΔG⁰) calculated from the temperature-dependent sorption isotherms suggest that the sorption of Co(II) on β-CD–GO is a spontaneous and endothermic process. The maximum sorption capacity of Co(II) on β-CD–GO (72.4 mg g⁻¹) at pH = 6.0 ± 0.1 and T = 303 K was much higher than that of Co(II) on GO (47.39 mg g⁻¹) and other sorbents. The abundant oxygen-containing functional groups of modified β-CD on the GO surface can improve the sorption capacity of β-CD–GO for Co(II). The results indicate that β-CD–GO is a promising material for the removal and enrichment of Co(II) from wastewater.